1. Field of the Invention
The present invention relates to a toner cartridge for use in an image forming apparatus such as a copying machine, a facsimile or a printer, and to an image forming apparatus in which the toner cartridge is mounted.
2. Description of the Related Art
In an image forming apparatus such as a copying machine, a facsimile or a printer, a toner cartridge functions to supply toner to a developing device and is detachably mounted in the image forming apparatus. The toner cartridge is detachably mounted in order to enable a user himself/herself to perform a replacing operation when toner in the toner cartridge runs short.
If a toner cartridge is mounted in the image forming apparatus, a cartridge holder which is disposed in the image forming apparatus is rotated. Thereby, the toner cartridge that is held by the cartridge holder rotates along with the cartridge holder and supplies a necessary amount of toner to the developing device.
A conventional toner cartridge comprises a toner container which contains toner, a shutter which opens/closes a discharge port that is formed in the toner container, and a cap which closes a filling port that is formed in the toner container. In other words, the conventional toner cartridge is composed of three pieces that are manufactured separately.
Of these components, the shutter is provided to be slidable relative to the discharge port of the toner container. By a mounting operation of the toner cartridge, the shutter opens the discharge port. By a removing operation of the toner cartridge, the shutter closes the discharge port. This prevents leak of toner when the toner cartridge is not mounted in the image forming apparatus.
However, even when the toner cartridge is mounted in the image forming apparatus, toner may, in some cases, leak from a gap between the toner cartridge and the cartridge holder. To prevent this, a seal member is provided to prevent toner, which is discharged from the toner cartridge, from flowing into the gap. The seal member is attached to the toner cartridge or cartridge holder, and the seal member is formed in an annular shape so as to surround the discharge port of the toner cartridge.
In usual cases, the toner container is formed of, e.g. polyethylene (PE) by blow molding. The blow molding is suited to manufacturing of hollow articles, and the cost of blow molding is low. Thus, the blow molding is a manufacturing method suitable for toner containers which are consumable components. However, the processing precision of the blow molding is low, and non-uniformity may, in some cases, occur in the dimensional precision of finished toner containers.
If the dimensional precision of the toner container is low, the insertion/positioning of the toner cartridge cannot precisely be performed. In some cases, such a problem will arise that the toner cartridge may contact a part of the image forming apparatus while it is being inserted or removed, and the seal member may be removed or the shutter is moved, resulting in leak of toner.